Device for monitoring the surroundings of a vehicle

ABSTRACT

A device is provided in a vehicle for monitoring the environment around the vehicle. The device includes a sensor system such that objects in a detection range of the sensor system are selected as a function of predetermined parameters so that only the selected objects are tracked by the sensor system. This permits adaptive use of reversible restraint means based on the sensor system output.

FIELD OF THE INVENTION

The present invention relates to a device in a vehicle for monitoringthe environment around a vehicle.

BACKGROUND INFORMATION

Published European patent document EP 550 852 A1 describes a device in avehicle for monitoring the surroundings, including an environment sensorsystem having a predetermined detection range, an analysis module beingprovided for analyzing a signal from the environment sensor system.

SUMMARY

The device according to the present invention in a vehicle formonitoring the environment around a vehicle has the advantage over therelated art that by selecting objects by interpretation of theenvironment and the situation, the environment sensor system limitsitself to pre-crash-relevant objects. This selection is advantageous forreporting only those objects which might actually result in an accident.This permits better differentiation between crash-relevant objects andnon-crash-relevant objects to prevent instances of misinterpretation.

It is particularly advantageous that the parameters according to whichthe device according to the present invention selects the relevantobjects include the relative speed between the vehicle and theparticular object, the direction of the relative speed, and the curveradius, as well as the type of traffic. The type of traffic isunderstood to refer, for example, to whether there is right-hand trafficor left-hand traffic. The device includes a sensor system having one ormore sensors which detect objects continuously. The detection range hasa fixed beam angle and a fixed range. A great many objects may bedetected in the detection range of the sensor system.

Depending on the driving situation, there are a number of parameterswhich make it possible to reduce the attention window. The attentionwindow is also based on the probability of occurrence of objects in thisrange.

First, there is the distance in front of the vehicle as a function ofthe relative speed or in a special case only the vehicle speed if thetime is fixed. Thus, for example, a reversible seatbelt tighteningdevice will always have the same activation time. Accordingly, theattention window must also be increased in the x direction as the speedsbecome higher, in order to provide the appropriate time for therestraint means, by tracking objects in a larger area.

The attention window in the y direction, i.e., in the transversedirection, depends on the relative speed between the vehicle and theobject. At high speeds, the probability for objects approaching thevehicle at a larger angle of approach is relatively low. Accordingly,the attention window in the y direction may be selected to be smaller.

The same is also true of passing vehicles, which occur every day onrural roads and communities. The distance from passing vehicles is afunction of speed.

The attention window in y direction is a function of the curve radius. Asmall curve radius requires a large attention window in the y direction.

For the interpretation of driving situations, another factor to be takeninto account is whether traffic is left-hand or right-hand traffic.Thus, in the case of right-hand traffic, automobiles being parked orautomobiles to be passed, and thus having a low relative speed, aredetected on the right. Vehicles coming from the opposite direction andcoming at a high relative speed are detected on the left.

In addition, it is advantageous that the analyzer unit of the deviceaccording to the present invention is connectable to at least onerestraint means, so that the analyzer unit triggers the at least onerestraint means as a function of the tracking of the at least oneobject. In particular, when the object is on a collision course withone's own vehicle and the distance is less than a threshold distance fordeploying a reversible restraint means such as seatbelt tighteningsystems, then the analyzer unit will generate a triggering signal todeploy the restraint means.

It is advantageous that the restraint means are designed to bereversible or at least partially reversible. This includes, e.g.,reversible seatbelt tightening systems or an extensible bumper.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of the device according to the presentinvention.

FIGS. 2 a and 2 b show two situations illustrating the functioning ofthe device according to the present invention.

FIG. 3 shows a flow chart of an example method according to the presentinvention.

DETAILED DESCRIPTION

In the future new functions will be developed for drivers to supportthem in driving a vehicle. These functions will include both comfortfunctions and safety functions. With regard to the safety functions, thepre-crash function will assume an important role because detecting animminent collision is extremely important in reducing the severity ofthe collision for the occupants of the vehicle. In particular it mayalso be possible to prevent the collision completely. However, it isproblematical that during a normal driving operation, many objects maybe detected in the area in front of a vehicle. According to the presentinvention, a device is provided for monitoring the environment andinterpreting the environment in order to select only those objects whichmight also be hazardous and crash-relevant in the sense of protectingthe occupants of the vehicle.

FIG. 1 shows a block diagram of an example embodiment of the deviceaccording to the present invention. A sensor system 1 is connected to ananalyzer unit 2 via a data output. Analyzer unit 2 is connected to acontrol unit for restraint means 3 via a data input/output. This controlunit 3 is in turn connected to a reversible seatbelt tightening system 4via a first data output, to an extensible bumper 5 via a second dataoutput and to airbags 6 in the vehicle via a third data output.

Sensor system 1 here includes distance sensors, which are alsounderstood to include environment sensors such as video, radar,ultrasound or even infrared sensors suitable for monitoring theenvironment. Control unit 3 is also connected to impact sensors (notshown here) which detect an actual crash. These may be accelerationsensors, but deformation sensors may also be used here. Sensor system 1supplies a digital data stream to analyzer module 2. Sensor system 1therefore has signal processing and an analog-digital converter.Analyzer module 2 may be a processor or dedicated hardware, i.e., anintegrated circuit produced for this purpose. Sensor system 1 andanalyzer module 2 may both be situated in one housing. However, sensorsystem 1 may also be situated in an offset position from analyzer module2, so that different video sensors mounted on the vehicle, for example,may be connected to just one analyzer module 2. With such an offsetconnection, it is possible for either each individual sensor of sensorsystem 1 to be connected to analyzer module 2 by a two-wire line, or foran entire sensor bus to be used to connect the individual sensors ofsensor system 1 to analyzer module 2, e.g., as a bus master. Theconnection may be implemented electrically, optically or via radiowaves. If analyzer module 2 is offset from sensor system 1, then thisanalyzer module 2 functions as a control unit and may, if necessary,also be set up in one housing with control unit 3. If analyzer module 2and control unit 3 are installed in different housings, then theconnection between them is implemented either by a two-wire line or by abus which interconnects a plurality of control units.

Control unit 3 itself calculates the deployment algorithm for restraintmeans 4, 5 and 6. The signal from sensor system 1 is also used to deployreversible restraint means, such as seatbelt tightening system 4 andextensible bumper 5, even before the impact. An adaptive airbag which isinflated relatively gently, i.e., with a short inflation time, mayalready be deployed before the actual collision. Other parameters thatenter into the deployment algorithm include the signals from the impactsensors, i.e., the acceleration sensors, for example, as mentionedabove.

According to the present invention, analyzer unit 2 selects from theobjects recognized by sensor system 1 those which might be relevant forcausing a collision, taking into account parameters such as the relativespeed between these objects and the vehicle, their direction, and thedriving situation, as well as the properties of the road surface. Thusthe available resources are used for the potentially hazardous objectsand not for non-hazardous objects, so there is no loss of performancedue to unnecessary tracking of irrelevant objects. On the other hand,due to the selection of objects the occurrence of misuse cases, i.e.,non-deployment cases in which the devices are nevertheless deployed, isprevented.

The selected objects are then tracked by sensor system 1. If analyzermodule 2 recognizes that an object being tracked is closer than apredetermined distance from the vehicle, a signal is transmitted tocontrol unit 3 indicating that the restraint means that are the first tobe deployed should be deployed. These include, e.g., reversible seatbelttightening systems. This predetermined distance around the vehicle isthus a time limit for the use of such restraint means. However, evenafter the distance drops to less than this predetermined distance, theobject is still tracked in order to be able to have precise informationregarding a possible future collision, to thereby achieve an adaptiveuse of restraint means. Several such distance values may be preselectedto determine an optimum time for deployment of the particular restraintmeans as a function of the respective deployment time.

FIGS. 2 a and 2 b show two typical situations for the use of the deviceaccording to the present invention. A vehicle 7 has a detection range 8for its sensor system 1, this detection range being monitoredcontinuously by the sensor system, e.g., by radar. If a vehicle 10enters detection range 8, this situation is detected by sensor system 1and parameters such as relative speed and its direction relative tovehicle 7 are determined. As a function of these parameters, anattention range 9 is defined having a predetermined distance 13 suchthat when an object such as vehicle 10 comes closer than this distance13, restraint means such as reversible seatbelt tightening device 4 aredeployed. The vehicle speed shown in FIG. 2 a is much higher than thatshown in FIG. 2 b, so the attention range 9 extends to the outer limitof detection range 8.

In FIG. 2 b, a vehicle 15 has a sensor system 1, having detection range8 and attention range 12. Here, too, distance boundary 14 is defined;when an object comes within this boundary, reversible seatbelttightening system 4 is deployed. Vehicle 11 is traveling transversely tothe direction of travel of vehicle 15. The relative speed betweenvehicles 15 and 11 is much lower here than that in FIG. 2 a betweenvehicles 7 and 10. Therefore, attention range 12 may be much smallerthan attention range 9.

FIG. 3 shows a flow chart for the method according to the presentinvention, which method may be run on the analyzer unit or module 2. Inmethod step 20, objects in detection range 9 are detected with the helpof sensor system 1 and analyzer module 2. The parameters are thendetermined in method step 21, with the relative speed between one's ownvehicle and the detected objects being determined in this case. Thedirection of the relative speed is also determined here in order to beable to estimate whether a collision is imminent. Additional parameterswhich may be considered include the curve radius and the type oftraffic, i.e., traffic on the right or left. Other data such as thedriving behavior of the other objects may also be included as parametershere. The individual parameters are weighted to derive a conclusion inmethod step 22 regarding which objects are relevant and must besubjected to tracking, which is performed in method step 23, to deploythe restraint means as soon as possible in the event of an imminentcrash.

In method step 24 monitoring is performed to determine whether theobjects tracked have a high likelihood of causing a collision with one'sown vehicle. This is monitored on the basis of predetermined distances13 or 14, namely whether an object is within these distances. If atracked object comes within such a safety distance, there is a switchfrom method step 24 to method step 25 to deploy the particular restraintmeans associated with this distance being breached. However, if acollision is not imminent based on the test in method step 24, trackingof the object is continued in method step 23. Several objects may betracked simultaneously, but this number should be as low as possible toachieve effective utilization of resources of the available hardware andsoftware. If the number of objects to be tracked is too high, theresponse time of the device according to the present invention may bereduced.

1. A device in a vehicle for monitoring the environment around thevehicle, comprising: an environment sensor system having a predetermineddetection range; and an analyzer module for analyzing a signal of theenvironment sensor system, wherein the analyzer module selects andtracks at least one object in the predetermined detection range bydetermining an attention range as a function of at least onepredetermined parameter, and wherein the attention range includes athreshold distance at which a restraint unit associated with the vehicleis triggered, wherein the threshold distance is selected to optimize,based on a duration required for deployment of the restraint unit, atriggering time.
 2. The device as recited in claim 1, wherein the atleast one predetermined parameter includes one of a relative speedbetween the vehicle and the at least one object, a direction of therelative speed, a curve radius, and a type of traffic.
 3. The device asrecited in claim 2, wherein the analyzer module is connected to at leastone restraint unit associated with the vehicle, the analyzer moduletriggering the at least one restraint unit as a function of tracking ofthe at least one object.
 4. The device as recited in claim 3, whereinthe at least one restraint unit is a reversible-type restraint unit. 5.The device as recited in claim 4, wherein the at least one restraintunit is one of a reversible seatbelt tightening system and an extensiblebumper.
 6. The device as recited in claim 1, wherein the thresholddistance is adjusted along a longitudinal axis and a transverse axis ofthe vehicle in response to changes in the at least one predeterminedparameter, the adjustment along the longitudinal axis being independentof the adjustment along the transverse axis.
 7. The device as recited inclaim 1, wherein a perimeter of the attention range is limited to thedetection range of the sensor system and conforms to a general shape ofthe detection range while varying in size according to the thresholddistance.
 8. The device as recited in claim 1, wherein the thresholddistance is adjusted along a longitudinal axis and a transverse axis ofthe vehicle in response to changes in the at least one predeterminedparameter, the adjustment along the longitudinal axis being independentof the adjustment along the transverse axis, and wherein a perimeter ofthe attention range is limited to the detection range of the sensorsystem and conforms to a general shape of the detection range whilevarying in size according to the threshold distance.
 9. The device asrecited in claim 8, wherein the at least one predetermined parameterincludes one of a relative speed between the vehicle and the at leastone object, a direction of the relative speed, a curve radius, and atype of traffic, wherein the analyzer module is connected to at leastone restraint unit associated with the vehicle, the analyzer moduletriggering the at least one restraint unit as a function of tracking ofthe at least one object.
 10. The device as recited in claim 9, whereinthe at least one restraint unit is a reversible-type restraint unit. 11.The device as recited in claim 9, wherein the at least one restraintunit is one of a reversible seatbelt tightening system and an extensiblebumper.
 12. The device as recited in claim 1, wherein the at least onepredetermined parameter includes one of a relative speed between thevehicle and the at least one object, a direction of the relative speed,a curve radius, and a type of traffic, wherein the analyzer module isconnected to at least one restraint unit associated with the vehicle,the analyzer module triggering the at least one restraint unit as afunction of tracking of the at least one object.